The invention relates to an arrangement for the breaking up and taking up of outer layers of the ground, such as, for example, frozen ground, concrete surfaces, asphalt.
In many cases it is necessary to break up and to remove outer layers that are relatively hard. It is frequently desired to restrict this only to limited areas, while adjacent zones are to remain unaffected. For example, in the laying of lines of different types it can be necessary to open up ditches, in which operation the ditches must in many cases cross asphalt-coated or concrete-coated surfaces, or surfaces provided with another coating. In other cases, too, it can become necessary to remove outer layers.
The sub-ground into which the ditches are to be made consists occasionally of cohesive soil. It can also happen, however, that the ground is rocky. For the digging of ditches, troughs, pits or other depressions, there serve as a rule dredges with corresponding dredge shovels. In order to enable the digging of ditches even in the case of difficult ground relations and in the case of sealed ground provided with relatively resistant outer layers (street paving), it has already been proposed to combine a dredging shovel with a milling arrangement. The milling arrangement is arranged on the open front of the dredging shovel.
When working in cohesive soils the use of a milling arrangement is frequently unnecessary.
In view of the foregoing an object of the invention is to create a versatilely usable device for the breaking up of outer layers of the ground. Furthermore, it is an object of the invention to create a corresponding process which permits an efficient operation.
In the arrangement according to the invention, a receiving arrangement that is configured for the taking-up and local removal of excavated material is combined with a milling and cutting arrangement which allows penetration through concrete stone or asphalt layers, or frozen ground. The milling and cutting arrangement is preferably constructed in such manner that it makes possible a more or less smooth cut which separates the areas to be broken up from zones that are not to be removed and that are to remain undamaged. If, for example, a trench is to cross a street, the pavement must be removed in the zone of the trench; the rest of the outer layer is not to be loosened up. Conventionally, a separating cut is made into the pavement with diamond saws, in order to prevent the possibility that in the opening of the trench relatively large parts of the adjoining pavement will be torn out or damaged. The milling and cutting arrangement makes the separating cut dispensable, and it removes the pavement only in the requisite zone. It has preferably a milling and cutting rotor which is provided with corresponding chisels and leaves an essentially smooth border cut. For the drive of the milling and cutting arrangement a drive arrangement is provided in the trench opening arrangement. A holding and guiding arrangement carries both the milling and cutting arrangement and also the receiving arrangement and the drive arrangement, which are firmly joined with one another, and it permits their positioning in order to mill ground layers and to excavate trenches.
The receiving arrangement has a free receiving opening; i.e. the milling and cutting arrangement is not arranged in the zone of the receiving opening of the receiving space. Thereby the undisturbed taking up of loosened rubble is possible independent from the operation of the milling and cutting arrangement. The arrangement can be altogether, if so needed, like a dredger shovel, without it driving the milling and cutting arrangement. The lift-off from cohesive soils, which under some circumstances could clog a milling and cutting arrangement, thereby becomes possible without hindrance.
The milling and cutting arrangement can have several motors. In a preferred embodiment, however, it has only a single rotor fitted out with chisels or other cutting tools. The latter is constructed as a disk or roller milling tool and permits a milling depth of at least 20 cm, but preferably of 30 cm or more. Thereby it becomes possible to excavate pavement and if necessary at least a part of the substructure in one operation. Furthermore it thereby becomes possible to get along with relatively narrow rotors, which do not extend over the entire width of the dredge shovel (receiving arrangement). This permits for example achieving relatively great milling depths with moderate performance of the drive arrangement. The removal of the outer layer over a trench to be opened occurs then in several working steps, as the outer layer is milled up stripwise, laterally offset.
The milling and cutting rotor is preferably accommodated in a chamber arranged on the rear side of the receiving arrangement, from which it projects with one section. Thereby it becomes possible to use the receiving arrangement and the milling and cutting rotor independent from one another. In the milling of ground outer layers or of relatively hard stone layers the receiving arrangement is not in the way and in the taking up of rubble the milling arrangement is not an obstruction. It is advantageous if the milling and cutting rotor has a diameter that is greater than half the height of the rear side of the receiving arrangement. Thereby again the above-mentioned great milling depths are possible.
The regulating of the milling depth occurs preferably by means of a support strip, support skid or support plate which is supported on the not-yet-loosened material of the outer layer. The strip, skid or plate can be arranged in a working direction in front of, or beside, the rotor.
Adjacent to the rotor and at a distance therefrom there is preferably arranged a stop strip, past which the chisels run. By regulating the spacing between the chisel pieces and the stop strip the granulation of the resulting fragmented material can be regulated. With suitable adjustment there is yielded a relatively uniform granulation of the material.
The receiving arrangement can have a flat underside. This is advantageous especially for the development of level trench bottoms. Here it is appropriate if the cutting and milling, in the case of a horizontally maintained underside, is arranged above the same. The axis of rotation of the milling and cutting rotor is arranged at a distance from the underside that is greater than the radius of the milling and cutting rotor, in order to make this possible.
Between the chamber receiving the milling and cutting arrangement and the receiving arrangement there can be arranged an inter-wall or partition. This can be made completely continuous in order to completely separate the milling and cutting arrangement from the receiving arrangement. If need be it is also possible to provide the partition with a passage opening. The passage opening is preferably arranged in the throwing zone of the milling and cutting arrangement. Thereby there is made possible a direct introduction of milled and fragmented ground layer into the receiving arrangement. The passage opening can be permanently open or can be provided with a shutter or with a slider.
The milling and cutting arrangement permits not only the rapid and simple releasing and loosening of outer layers to be removed, but simultaneously their fragmentation to a grain size or to grain size ranges that permit the reinstallation of the milled and fragmented material as recycled material instead of ballast. The granulate generated by the milling process can be introduced directly into the receiving space of the receiving arrangement through a corresponding above-mentioned passage opening in the partition. If the partition is constructed as a sieve, at least in zones, or provided with a sieve, the milled material can be fragmented by the rotor and classified in one operation. Into the receiving space there passes only the constituent with the desired granulation, while coarser parts are exposed further to the rotor and broken up or allowed to lie there. This saves drive power and allows the generation of recycling material of high and uniform quality.
Alternatively, the granulate can at first remain in situ and then be taken up by the receiving arrangement in a second working operation. With the last-mentioned manner of operation parts of the released outer layer or fractions of same remain relatively longer in interaction with the milling and cutting rotor, so that there is possibly yielded a stronger or also more uniform fragmentation of the material. Independent of this, the inventive arrangement permits a separate acquisition of fragmented outer layers and of cohesive material lying under them. To this there contributes again the feature that the milling and cutting rotor preferably does not occupy the entire width of the receiving arrangement (dredge shovel). Beside the milling and cutting rotor there can be provided a control arrangement which establishes the milling depth. The guide arrangement can be formed by a guide surface range, a guide edge or a skid, which is seated on not-yet-excavated outer layer material, and slides along this. Thereby there is prevented too deep a penetration of the trench-opening arrangement into the ground in the milling-opening of the outer layer, and therewith an unintended taking-up of cohesive underground material.
If need be, here an adjustable guide element can be provided in order to adjust the milling depth. Alternatively, the position of the axis of rotation can be made adjustable, which again permits an adjustment of the milling depth. Under some circumstances this can also occur by use of different-sized rotors. In most cases, however, at least in the case of simplified embodiments, because, in many cases a uniform covering thickness is encountered in pavements, it is possible to dispense with adjustment of the milling depth.
The reinstallment of the milled covering material instead of ballast saves depositing costs and spares the environment. Furthermore, costs for the acquisition of ballast are saved, which is mostly requisite anyway.
Also the cohesive ground can be reinstalled, if need be. For this it may, if necessary, be treated with additives. For the mixing of the cohesive soil with the additives, if need be, the milling and cutting rotor can be drawn upon. First of all, the additive substance is applied to the cohesive soil, after which it is milled in by the milling and cutting rotor. This can occur before or after the excavation of the ground in situ, on the loading surface of a truck, or on an intermediate storage surface.
The arrangement is preferably provided with, or is connectable with, a weight which presses the cutting and milling arrangement against the outer layer to be broken open. With such a weight, however, not only is there brought about a contact-pressure effect, but simultaneously there is achieved a strong damping of vibrations. Wear-promoting vibrations or vibrations undesired for other reasons are absorbed near the point of origin, i.e., near the milling tool, by the mass inertia of the weight, and are thus eliminated. This makes possible again high milling performance even in the case of highly resistant outer layers.
The weight can be formed by a steel ball to be taken up by the arrangement, an otherwise constructed weight or, for example, also an especially heavily constructed outer lid element, which is swingably borne in front of the receiving opening. The outer lid element there can be both removable, freely pivotable or hydraulically pivotable. The outer lid element has the advantage of leaving the receiving space free, so that this space at least in the embodiment with a passage opening or openings between the milling tool and the receiving space, can be filled with milled material.